N-methylene phosphonic chitosan: a novel soluble derivative

A novel water-soluble chitosan derivative carrying phosphonic groups was synthesized using a one-step reaction that allowed homogeneous modifications without any sharp decrease in its properties, such as filmogenic capacity (this compound and its synthesis have been protected with a patent). The 1H NMR, 13C NMR assignments and 1H–13C NMR correlation permitted the identification of the structure by the subtituent distribution of the product, which is partly N-monophosphonomethylated (0.24) and N,N-diphosphonomethylated (0.14) and N-acetylated (0.16) without modification of the initial degree of acetylation. The identity of the N-methylene phosphonic chitosan was confirmed by FT-IR spectrometry, X-ray diffraction and elemental analysis.Taking advantage of the known chelating ability of the phosphonic groups, especially for calcium, this new derivative opens new perspectives as biomedical material.